@Roronoa:
How can I put it? Luffy's thoughts on this alliance are obvious and simple: "We're friends." whereas Law rather looks at it from a more rational, "business"-side (like BigMom did with FI: only business and candy, no emotions).
That's clearly a running gag!
And Oda lets it seem like Law doesn't want a deeper bond with Luffy (like the minks and the Wano-guys have).
The bond has already been made by making Law a 'D' and Law is well aware of it.
If things get messy AFTER Kaidou I COULD think of Law at least abandon the SHs. Right now Law needs 'em, but who knows what happens after Kaidou's defeat.
Law also now knows bout the road-poneglyphs and was pretty silent in that chapter.
He'll just leave for the time being and not say a dumb line like "We'll be enemies next time we meet".
Law had no saying on the poneglyphs talk when Robin is present, that's just free knowledge for him.
It could also be that Law doesn't show his feelings and stuff
Law is just another Zoro, act cool and butt in when the time needs it.
If people really want someone to betray Luffy, they should be looking at Kidd more than anybody else on the serie.